1. Field of the Invention
This invention relates, generally, to the art of prosthetics. More particularly, it relates to a cushioned liner worn on a residual limb.
2. Description of the Prior Art
A cushioned liner is worn on a residual limb, much like a sock, to provide a comfortable interface between a residual limb and a prosthetic socket. If the liner has an air-impermeable structure, it can also serve to maintain a vacuum in the space between the distal end of the liner and the distal end of the socket. Such a vacuum may be harnessed to retain the liner within the socket.
Several suppliers make cushioned liners having a gel-covered interior and a fabric exterior. The gel fits comfortably against the skin of the user and the fabric slides smoothly into the prosthetic socket.
A liner having a gel interior may be somewhat difficult to put on, especially if the user is elderly or lacks physical flexibility for some other reason. Arthritis or other similar condition can also add to the difficulty in donning a liner. To put on a gel-lined liner, it is first turned inside out so that the gel is on the outside and the fabric is on the inside. The user places the distal end of the gel against the distal end of the residual limb and progressively restores the liner to its initial, fabric-out, gel-in configuration by reversely bending the liner at the distal end thereof and rolling the bend toward the proximal end of the residual limb. The reverse bend progresses up the residual limb until the initial configuration is fully restored.
A residual limb having cicatricial tissue and scarring is more problematic because such condition tends to cause more air entrapment than normal. The liner is put on in the same way, but then the user must apply heavy finger pressure to the liner where it overlies the scarred tissue, and progressively work any air thereby liberated up to the proximal end of the liner so that it can escape. Patients who have pain or little strength and flexibility in their fingers cannot perform such procedure adequately and are therefore denied the comfort that a gel-padded liner can afford.
The purpose of the donning procedure is to eliminate air pockets between the residual limb and the liner. It is important that no air remains between the residual limb and the interior surface of the liner, particularly at the distal end of the liner. An alternating suction action, sometimes called a xe2x80x9cmilkingxe2x80x9d action, is applied to the residual limb during ambulation if air is left inside the liner. Blood may collect in the distal end of the residual limb, leading to rupturing of blood vessels or opening of sutures.
Most amputations in industrialized countries are due to vascular disease or diabetic complications. A diabetic patient may have little or no sensation in a residual limb and may be unaware that a rupturing of blood vessels or sutures has occurred. It is not unusual for such patients to be unaware for long periods of time that the distal end of their residual limb has been severely damaged. As a result, there may be a long delay in seeking help, with the result that additional surgery may then be required to remove even more of the residual limb.
What is needed, then, is a prosthetic liner that prevents the entrapment of air between a residual limb and a prosthetic liner during ambulation.
More particularly, there is a need for a liner that may be donned in the absence of a great degree of care so that a user lacking physical strength, flexibility, and manual dexterity may use such a liner without risk of causing injury to the residual limb, even if the liner entraps substantial quantities of air when the liner is put on.
However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how such needs could be fulfilled.
The long-standing but heretofore unfulfilled need for an improved liner construction is now met by a new, useful, and nonobvious invention.
The novel liner includes an interior surface formed of a soft gel adapted to abut and overlie a user""s residual limb and an exterior surface formed of a flexible fabric adapted to abut and underlie an interior surface of a prosthesis. The interior surface and exterior surface are bonded to one another substantially throughout the liner. A one-way air expulsion valve is disposed between the interior surface and the exterior surface in a preselected area of the liner. The interior surface and exterior surface are unbonded to one another in the preselected area to accommodate the one-way air expulsion valve. An air passageway is formed in the interior surface in fluid communication with an inlet of the one-way air expulsion valve and the one-way air expulsion valve is positioned such that air entrapped between a residual limb and the interior surface of the liner escapes such entrapment by flowing through the air passageway, into the inlet, and out an outlet of the one-way air expulsion valve when the user ambulates. The air from said outlet flows through the fabric into a space bordered by a distal end of the liner and a distal end of the prosthesis. Air entrapped between the residual limb and the liner is adapted to flow into said space and air in said space cannot flow in a reverse direction to re-enter the liner.
The one-way valve may take the form of a flapper valve, a duckbill valve, an umbrella valve, or any other suitable check valve means. The one-way valve is disposed at or near the distal end of the liner.
An important object of this invention is to provide a liner having a structure that allows air entrapped between a residual limb and a liner to escape before it can cause injury to the residual limb during ambulation.
A more specific object is to provide a liner where entrapped air escapes as a result of ambulation of the user.
Another more specific object is to provide a liner having a one-way air expulsion valve disposed at or near its distal end through which air flows until substantially no air remains within a space between a residual limb and the liner.
These and other important objects, advantages, and features of the invention will become clear as this description proceeds.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims.